Long distance travel by air and motor vehicle as a passenger without exercise and movement of the leg is associated with serious health risks. They are related to lower extremities which are the dependent lowest part of the body during these travels. Gravity and lack of exercise or movement of dependent legs during long air travel and vehicular travel are associated with ankle edema, venous blood pooling in dependent legs, deep vein thrombosis (DVT) of the leg veins, and pulmonary emboli (PE) if thrombus is dislodged from the leg vein, which can threaten the life.
All over the world especially in US, commercial air travel is one of the safest, reliable, dependable methods of transportation; short and long distances from one place to another. Millions of people of all ages take to the air every day. Due to super highways, the long travel in automobiles, passenger buses, SUVs, and recreation vehicles, traveling is part of our lives without breaking to exercise the leg and where the leg rests on the floor of the vehicle with untold discomfort to the passenger and with the leg swelling with or without deep vein thrombosis.
The environment within the aircraft and seating with hardly any space to move the lower limbs in the cabin may have adverse pathological effects on passengers, especially in the elderly and those with underlying medical problems (Voss M W. Air travel for the chronically ill and elderly. Am Fam Physician 1983; 27: 235-43).
The cramped up, overcrowded, confined, restricted conditions, prolonged immobility (particularly in long-air flights), constant noise and vibration, and intermittent air turbulence may be disturbing to the air (and surface vehicular as well: Bus rides, cars, SUVs and RVs) travelers. It can cause edema of the lower limbs (jet flight leg) which is the commonest complication of air travel; deep vein thrombosis (DVT) (‘economy class syndrome’) as a result of venous stasis in the dependent leg and Pulmonary Embolism (PE) if the thrombus gets loose and travels to the lungs through the venous highway of our body. There is a detailed review on the “air travel in older people” by James A. Low, Daniel K, Y. Chan in Age and Ageing 2002; 31: 17-22).
Physiological Effects of the Air Cabin on the Traveler
Air plane cabin pressure varies according to the altitude. Most commercial planes travel between 28,000 and 45,000 feet (flight altitude) above sea level with cabin pressures maintained between the equivalents of 6000 to 8000 feet (cabin altitude) above sea level. Cabin oxygen starts decreasing at altitude above 22,500 feet. At a cabin pressure of 6,000 feet, the alveolar oxygen tension is 71 mm Hg while at 8,000 feet it is 59 mm Hg (AMA Commission on Emergency Medical Services. Medical aspects of transportation aboard commercial aircraft. J Am Med Assoc. 1982; 247: 1007-11). At cruising altitude, cabin oxygenation is diminished and may pose a health risk to passengers with anemia, cardiopulmonary illnesses, emphysema, COPD, and other vascular conditions. This can result in carbon dioxide build up and acid metabolites accumulation due hypoxic metabolism (lactic acidosis) in the body further contributing to the pathology of leg edema and DVT.
Further, the low cabin pressure leads to expansion of gases in accordance with Boyle's law. If gas is trapped in body cavities such as the sinuses, middle ear, gut, pleural cavity, emphysematous bullae, eyes, tooth fillings, and skull, this can be hazardous to health due to difficulty equalizing air pressures within these enclosed areas of the body with the external environment. It can cause aerotitis media, barosinusitis, aerodontalgia, pneumothorax, transient ischemic attacks, nausea, and vomiting.
The air in the cabin has low humidity. The low humidity (usually below 25%) within the cabin may lead to dryness of exposed membranes (oropharynx and eye), which leads to dehydration, if the traveler is on a diuretic and the ingestion of many alcoholic drinks during the flight.
The overcrowded, confined, restricted conditions, prolonged immobility in long flights and surface travel, constant noise, and vibration of the plane; and intermittent air turbulence due to weather and altitude changes may be disturbing to travelers specially if the person is elderly (Rayman R E. Passenger safety, health and comfort: a review. Aviation Space Environ. Med. 1997; 68: 432-40). To top it all, prolonged air travel can cause edema of the lower limbs (jet flight leg) (Shuster S. Jet flight leg. Lancet 1996; 347: 832-3. James P B. ‘Jet leg’, pulmonary embolism and hypoxia. Lancet 1996; 347: 1697.), or deep vein thrombosis (‘economy class syndrome’) (Cruickshank J M, Gorlin R, Jennett B. Air travel and thrombotic episodes: the economy class syndrome. Lancet 1988; ii: 497-8.), as a result of venous stasis due to lack of leg muscle exercise which literally pumps blood towards the heart during contraction in the unidirectional valves of the leg veins.
Pulmonary embolism is now a well-recognized complication of long-haul air travel (Black J. Deep vein thrombosis and pulmonary embolism. Lancet 1993; 342: 352-3. Milne R. Venous thromboembolism and travel: is there an association. J R Coll Physicians Lond 1992; 1: 47-9. Lederman J A, Keshavarzian A. Acute pulmonary embolism following air travel. Postgrad Med J 1983; 59: 104-5).
A study of 56 victims of pulmonary embolism at Charles de Gaulle Airport found a direct correlation between the distance traveled and the likelihood of PE. About 85% of air travel thrombosis victims (DVT) are athletic, usually endurance-type athletes like marathoners. People with slower resting blood flow are at greater risk of stasis, stagnant blood subject to clotting. Also, they are more likely to have bruises and sore muscles during their athletic activities that can trigger clotting in the stagnated blood in the blood vessels of the lower extremities. It is estimated that chances of blood clotting in the leg veins is fifty times more in fliers compared to non-flying population.
Development of acute ischemia due to arterial thrombosis of the lower limbs from prolonged sitting is one the complications cannot be ignored (Teenan R P, McKay A J. Peripheral arterial thrombosis related to commercial airline flights. Br J Clin Pract 1992; 46: 165-166).
Hypoxia during flying can induce ischemic conditions of the heart, leading to acute myocardial infarction or stroke, or change in cognition. Older people may suffer the harmful effects of prolonged hypoxia without presenting overtly initially. The cardiac consequences of in-flight hypoxia include angina, acute myocardial infarction, and congestive cardiac failure (Anon. Illness in the clouds (editorial). Br Med J 1975; 1: 295). Cardiac conditions constitute the most common cause of in-flight deaths (Cummins R O, Chapman P J C, Chamberlain D A el al. In-Air flight deaths during commercial air travel. J Am Med Assoc. 1988; 258: 1983-8.).
PE deaths each year are numbered about 200,000. Several studies, such as a 4-year study at Tripler Army Medical Center in Hawaii, have concluded that 50% of DVT/PE cases are attributable to air travel. Of 200,000 PE deaths the 50% are due to air travel would be 100,000. This is a conservative estimate because it doesn't include stroke and heart attack deaths caused by air travel DVT. About 48% DVT victims later develop so called Postthromoteic syndrome (PTS) resulting in swelling and pain of the lower leg. Due to these lingering health risks due to air travel, precautions should be taken to prevent the leg swelling, and venous stasis in leg veins.
One of the most common in-flight medical emergencies is syncope (fainting fit) from a variety of causes (Cottrell J, Callaghan J, Kohn G el al. In-flight emergencies: one year of experience with the enhanced medical kit. J Am Med Assoc 1989; 262: 1653-6. Donaldson E, Pearn J. First aid in the air. Aust N Z J Med 1996; 66: 431-4. Schoken V, Lederer L. Unscheduled landings for medical reasons: a five year survey of the experience at American Airlines. In Busby D edited. Recent Advances in Aerospace Medicine. Dordrecht: Reidel, 1970; 126-9.).
Aircraft passengers, especially elderly travelers, are more prone to syncope because of prolonged sitting with pooling of the blood in dependent leg, dehydration and alcohol use if there is any which can lead to postural hypotension and syncope (Jagoda A, Pietrzak M. Medical emergencies in commercial air travel. Emerg Med Clin North Am 1997; 15: 251-60).
Economy Class Syndrome and Jet Leg Syndrome
The term ‘economy class syndrome’ refers to the development of deep vein thrombosis with subsequent pulmonary embolism in passengers travelling long distances in the cramped economy class seats. Unfortunately, the business class and first class travelers, pilots and air hostesses are not exempt from these risks. This term can be applied to the long distance bus rides, SUV, and car travel.
Those with predisposing medical conditions such as venous system disease (Varicose veins), advanced cancers, heart failure, atrial fibrillation, nephrotic syndrome, abnormally high hemoglobin (hematocrit) levels, hemochromatosis, liver cirrhosis, high platelet levels, leukemia, hypercoagulable disorders, women on hormonal therapy, history of recent surgery, and those with a history of thrombo-embolic illnesses are at a risk of developing this complication (Symington I A, Stack BHR. Pulmonary thromboembolism after travel. Br J Dis Chest 1977; 71: 138-40. Sarvesvaran R. Sudden natural deaths associated with commercial air travel. Med Sci Law 1986; 26: 35-8. Thomas J E P, Abson C P, Cairns N J W Pulmonary embolism: a hazard of air travel. Centr Afr J Med 1981; 27: 85-7).
Dependent leg with edema, pooling of venous blood in the legs, and DVT can result in pulmonary embolism (PE) due to air travel and journeys as short as 4 hours. DVT may present 1-2 weeks after the flight or long vehicular travel and is not necessarily preceded by a pain in the calf. Preventive Measures suggested include the use of pressure-graded elastic stockings (not elastic panty hose, they won't help), periodic muscle contracting exercises while seated using our invention, regular walks from the aisle seat (avoiding the window seat if possible), restrict excessive alcohol intake, and adequate (non-alcoholic) electrolyte fluid intake (Landgraff A. Economy class syndrome: theology, balance and lower leg edema during a simulated 12 hour long distance flight. Aviat Space Environ Med 1994; 65: 930-5).
Travelers with predisposing conditions who are at a high risk for thrombo-embolism; low-molecular-weight heparins, warfarin or low-dose aspirin may be taken prophylactically (The Pulmonary Embolism Prevention (PEP) (Trial Investigators. Prevention of pulmonary embolism and deep vein thrombosis with low dose aspirin. Lancet 2000; 355: 1295-302. Kay S. Safe air travel. Preventing in-flight medical problems. Nursing Pract 1994; 19: 43-6.). Leg edema ('Jet flight leg'), may mimic deep vein thrombosis, is more common in women, usually benign, resolves spontaneously and can be prevented by the use of appropriate elastic stockings, which should be worn before take-off to be effective as soon as you are seated in the plane and using our invention. They can be worn during long bus, car, and other vehicular rides also.
Air Cabin Effects on Body Gases of Passenger
The expansion of body gases within the low-pressure environment of the aircraft cabin can cause serious harm to health. Expansion of gases within the stomach and duodenum may lead to pain, discomfort, nausea, vomiting, splinting of the diaphragm, breathing difficulties, and even intestinal perforations. Hence, avoid gas-producing foods before travel and carbonated drinks during the flight. Those with recent abdominal (gastrointestinal and urological) surgery, gastrointestinal hemorrhage, or bowel obstruction should refrain from flying till health is restored (2-3 weeks after the event). For those with a colostomy, a larger bag should be used and carry a spare bag to the cabin. The trapped air in defective teeth fillings, apical abscesses and carious teeth can expand to cause toothache (aerodontalgia).
Cardiac conditions constitute the most common cause of in-flight deaths (Cummins R O, Chapman P J C, Chamberlain D A el al. In-Air flight deaths during commercial air travel. J Am Med Assoc 1988; 258: 1983-8.). Air travel should be avoided in those with new or unstable angina, history of recent myocardial infarct (within 3 months), poorly controlled congestive heart failure, malignant hypertension or severe anemia<8 g/dl), advanced COPD, severe lung fibrosis and cardiac asthenia.
Ear and Sinus Problems During Air Travel
Ear and sinus problems are the recurring complaints of the travelers during ascent and descent of the air plane. Earache can be serious and annoying in toddlers (crying due to pain). Otic barotrauma occurs in up to 9% of air travelers. It can present as acute ear pain, tinnitus, vertigo, or temporary hearing loss (Csortan E, Jones J, Haan M Brown M. Efficacy of pseudoephedrine for the prevention of barotraumas during air travel. Ann Emerg Med 1994; 23: 1324-7.).
Cabin pressure changes can be deleterious to passengers with middle ear and sinus problems. Failure to equalize pressure within the middle ear and the environment can cause otic barotrauma and potentially even tympanic membrane rupture with slight bleeding to external ear canal. A patent Eustachian tube is of paramount importance in equilibrating middle-ear pressure with the external environment. Individuals with acute otitis media, Eustachian blockage, and severe sinus problems; recently eye or brain surgery, lung surgery or laparascopic procedures are advised not to fly until the conditions are cleared. Passengers are advised to perform a Valsalva maneuver or to swallow repeatedly to prevent damage to the ear drum and open up the connection to the middle ear through the Eustachian tube.
Neurological Conditions and Effects of Air Travel
Seizures patients should be on medications and patients who have had strokes, after brain surgery or concussion within 4 weeks of occurrence should not travel to prevent further brain swelling and or recurrence during flight. Passengers (especially aged), due to prolonged sitting, dehydration and alcohol use, can lead to postural hypotension and develop Syncope (fainting).
Motion Sickness of Air Travelers
Air turbulence due to a linear vertical motion (during takeoff and landing descent) on the vestibular organ, psychological factors, and alcohol consumption can cause motion sickness, which can be incapacitating. Measures that can be used to reduce this problem include flying at night to reduce visual stimulation, sitting in a reclining position, seated away from the engines and toward the center of gravity of the aircraft, and taking prophylactic anti-motion medication during the flight such as anti-histamines and scopolamine patches.
Precautions for the Older Air Traveler
Due to aging of the population, the increased old age group travelling is increasing with resulting in multiple health-related medical emergencies in flight. In-flight medical emergencies can be reduced or averted with careful pre-flight planning and medical evaluation of those with many medical problems who are on multiple medications, those recently discharged from hospital, those with advanced chronic illness (such as heart failure or chronic airflow limitation) and those who are frail (Gong H Jr, Lee J A, Cowan M N.
Pre-flight medical screenings of patients. Analysis of health and flight characteristics. Chest 1993; 104: 788-94). All passengers over 65 who intend to fly for more than 6 hour should be screened for any health problems as a precautionary measure. Screening of patients susceptible to the adverse effects of hypoxia might include arterial blood gasses, an electrocardiogram, lung function tests, and measurement of serum hemoglobin concentration. All elderly people with memory or cognitive deficits are screened with the Mini-Mental State Examination. Those with early dementia may be more prone to developing delirium in flight.
The physician who deals with older patients should be able to offer advice, counseling, and screen those who are at risk and advice against travelling in certain situations (Table 1). Some recommendations are given in Table 2 if one has to travel.
There is a detailed review on the “air travel in older people” by JAMES A. Low, DANIEL K, Y. CHAN in Age and Ageing 2002; 31: 17-22; and has information for those who have to travel on long distance bus rides, recreation vehicles, SUV, and cars. The following tables are modified from this publication which acts as helpful guide lines for safe trip and to prevent leg swelling and deep vein thrombosis associated pulmonary emboli. Table I and Table II describe the health related contraindications and precautions to be taken if the travel is planned by the aged.
TABLE IContraindications to long-distance air travel speciallyfor the agedCARDIOVASCULAR SYSTEM1Heart attack within last 3 months2Chest pain due to unstable angina3Heart disease with uncontrolled congestive cardiac failure4Uninhibited cardiac dysrhythmias5and very high blood pressure (Malignant hypertension)RESPIRATORY SYSTEM1Air between the chest wall and lungs (pneumothorax)2Severe Emphysema with bullous (Air bubble pockets) disease3Vital capacity of <50%4Arterial P02 of <60 mmHg with oxygen at ground levelNEUROPSYCHIATRIC DISORDERS1stroke within last 4 weeks on anti-coagulants2Epilepsy - uncontrolled3Severe dementia with deliriumOTHERS HEALTH CONDITIONS1Severe anemia <8 g/dl)2Recent eye, abdominal or brain surgery (within last 2 weeks)3Serious sinus and middle ear infection
TABLE 2Recommendations for air travel specially to the agedBEFORE THE TRIP PREPARATIONS1Start preparations early - one to two weeks ahead2Consider travelling with family and groups3Foreign travel should include appropriate vaccinations3Take out adequate travel health and life insurance4Those with cardiopulmonary conditions, recent acute medical5Ask your doctor to prescribe anxiolytics for anxiety and6antihistamines for motion sickness to be taken before the Right7Involve in exercise program such as walking, swimming, cycling,tread mill etc.DURING THE FLIGHT OBSERVATIONS1Carry physical health aids2Carry medications in separate bag packed for easy accesses3If old, try to be seated along the aisle, away from the engines4Do not drink alcohol5Avoid gas-producing food such as beans you already know.6Avoid plain water, colas and drink electrolytes (Gatorade)containing fluids throughout the flight7Stop smoking a week or two ahead if you are habitual smoker8Once seated, take regular walks in the aisle and engage in legmuscle contracting movement exercises
If a blood clot dislodges from the leg veins due to movement of the leg after air flight and vehicular travel trek to the lung, which can cause pain, fainting, and even death. A clot in the leg is called deep vein thrombosis (DVT) and a clot in the lung is called pulmonary embolism (PE). Clots form in the arterial system and in the heart, leading to heart failure, and stroke about 2-3 weeks after travel.
DVT is usually mistaken for a cramp. Correct diagnosis and treatment is usually delayed which aggravates the injury and increases the risk of permanent vein damage and further injury or death when a clot travels to the lungs, brain, or heart. Airhealth.org says, “About 85 percent of air travel thrombosis victims are athletic, usually endurance-type athletes like marathoners. People with slower resting blood flow are at greater risk of stasis, stagnant blood subject to clotting. They are more likely to have bruises and sore muscles that can trigger clotting. Long bus and vehicular riders are not immune from this medical complication.
During air travel, blood coagulability (blood clotting) rises steadily and blood flow slows down, especially in the lower dependent part of the legs. Most of these clots are painless which some clots do cause pain and swelling. Blood clotting factors during a 9 hour flight (or vehicular rides) show noteworthy changes in blood chemistry.
Coagulation involves a complicated interplay between factors that produce fibrin versus factors that dissolve fibrin. DVT may appear during flight and vehicular travel or in the next few days. After 30 days you are probably safe. Watch for the following leg symptoms: 1. A little swelling in both leg is normal in flight but a sudden swelling in one lower leg is dangerous; 2. Cramp or tenderness in one of the calf muscles; 3. Bruise or swelling behind knee. Suspect PE if one develops the following: 1. Shortness of breath, 2. Rapid breathing, 3. Cramp in the side of chest wall, chest pain, sometimes accompanied by shoulder pain, painful breathing, 4. Fever, 5. Coughing up blood 6. Fainting (especially in older people).
Aspirin and clopidogrel (Plavix), are effective for arterial clotting and aggregation of platelets. They are not as effective for venous pooling and clotting. Low molecular weight heparin (Lovenox and Pinokinase) a new pharmacologic compounds effectively prevents blood clots during air travel.
Preventive Measures for Leg Swelling, DVT and PE
Frequent leg flexing and movement with contraction of the all the leg muscles is the best preventive for Air and long surface travels. The blood needs to be pressed through the one-way valve veins system by contractions of the thigh and calf muscle every 30 minutes and more often if you have RISK FACTORS.
Exercises:
1. Extend your leg and flex your ankles, pulling up and spreading your toes, then pushing down and curling the toes. If your shoes limit toe movement, make the effort and don't worry, or remove the shoes. Alternative: rotate the ankles, making circles in the air with your toes.
2. If there isn't room to extend your leg, start with your feet flat on the floor and push down and curl your toes while lifting your heels from the floor. Then, with your heels back on the floor, lift and spread your toes. Repeat this heel-toe cycle five times or more.
3. Exercise your thigh muscles by sitting with your feet flat on the floor and slide your feet forward a few inches, then slide back and repeat and extend the leg (if you have enough room), and isometrically flex thigh muscles.
Compression Stockings: Compression stockings have proven effective in controlled studies. Studies using ultrasound scans before and after air travel found 5% of air travelers without stockings developed clots. Matched groups wearing compression stockings did not develop clots. Compression stockings are not recommended for people with poor leg circulation caused by arterial insufficiency. Avoid elasticity along the entire length elastic “support” hose and use special graduated compression stockings which are tight at the ankle. The compression stockings helps keep fluids in circulation instead of collecting in the lower leg, causing the swelling that can make it difficult to get your shoes back on after a flight.
Hydration: In a study by Hamada, twenty test subjects drank plenty of water, one cup per hour, during a nine-hour flight. They developed significant increases in blood thickness and urine output. Blood samples from arms and lower leg were taken. Viscosity (thickness) increased in the lower leg, exactly where clots are likely to form. Twenty other people drinking an electrolytic beverage did not have increased blood viscosity and urine output.
According to Medline Plus “Electrolytes exist in the blood like acids, bases, and salts (such as sodium, calcium, potassium, chlorine, magnesium, and bicarbonate) and can be measured by laboratory studies of the blood serum.” Glucose is a carbohydrate; not an electrolyte. Apparently drinking an electrolytic beverage is a much better choice for staying hydrated during air travel (Hamada, Koichiro et al—Effects of Hydration on Fluid Balance and Lower-Extremity Blood Viscosity during Long Airplane Flights. JAMA. 2002; 287:844-845. February 20). Airlines don't serve electrolytic beverages which you may have to bring your own. Drink one cup per hour, for an eight-hour flight you need 64 ounces.
Tips to Reduce Lower-leg Swelling during Travel
1. Prevent wearing tight stretched, unyielding, skin-tight.
2. Drink adequate fluid to keep your urine light in color.
3. Include an isotonic drink such as Gatorade, Snapple etc. Isotonic means a solution that has the same salt concentration as the normal cells of the body and the blood as opposed to a hypertonic solution or a hypotonic solution.
4. Attempt to move your leg and stretch your ankles every 30 minutes by a short walk if possible or moving the leg while sitting. Draw circles with your toes to rotate your ankles if you are stuck in one position and cannot walk.
5. Elevate your feet and leg when possible. This is where our inventions play a major role in preventing the leg swelling and its associated complications such as DVT, and pulmonary emboli. You can elevate the leg any level you want using the present invention during any long travel.
6. Stay away from alcohol and sedatives because they both promote inactivity.
7. Consider wearing proper compression stockings. Do not confuse compression stockings with support stockings.
8. Avoid sleeping with crossed leg on the seat.
Many, who travel regularly, do not take the above precautions. We made a survey and observation at the airport and bus ports, which we found hardly anyone wearing compression stockings or taking any other measures enumerated here. Drinking alcohol was common in the first and business class. Only one time, we found a lady exercising her body from head to toe in the economy class. Majority of the people who walked out after flying had swelling of the ankles especially the elderly and females. Many of them had difficulty in walking (limping) due to increased tightness of the shoes at the ankle and leg due to swelling.
There is a need for an device that positions and suspends the leg above the floor in a vehicle passenger seat that is positioned behind a head rest to allow free movements of the leg (i.e. muscle contractions) that are bent at the hip, knee, and ankle resulting in prevention of venous blood pooling responsible edema and for deep vein thrombosis.